Benzophenone-azine is an important intermediate for the production of hydrazine as disclosed in U.S. Pat. No. 4,239,741, and development of an economical process for the production thereof has been long desired.
Of conventional processes for producing benzophenone-azine comprising contacting benzophenone-imine with molecular oxygen in the presence of a cuprous halide, a process using cuprous chloride as a catalyst is widely known as disclosed in U.S. Pat. No. 2,870,206. In this process, it is desired that the catalyst used be recovered and reused in the production of an industrial scale.
The above-described U.S. Pat. No. 2,870,206 discloses a process wherein aqueous ammonia or an ammonium chloride aqueous solution is brought into contact with the reaction system to extract the catalyst, which is then removed from the reaction system. This U.S. patent, however, does not refer to reuse of the catalyst that would bring about an industrial advantage.
Further, Japanese Patent Application OPI (Open to Public Inspection) Nos. 71045/78 and 38346/80, etc. disclose processes in which water, aqueous ammonia or a salt solution is added to the reaction system to precipitate a copper salt, which is then recovered. However, these processes involving precipitation of a copper salt are disadvantageous in that troublesome operations inevitably associated with handling of solids, such as filtration, separation of a precipitate, transportation of a slurry, etc., are required.